Possible resolution to my moronically low timing map values. - Miata Turbo Forum - Boost cars, acquire cats.

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Old 04-14-2008, 09:58 PM   #1
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Default Possible resolution to my moronically low timing map values.

So I had a mystery issue with my car. The timing was really, really low.



Yeah, that low. So someone here mentioned I should ensure my timing is set correctly, so I went ahead and did that. I stuck a screwdriver in the first spark plug, spun the motor around until the screwdriver said that plug was at TDC, and checked the marks.

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On the money. So then my friend (crashnscar) and I discussed the issue a little bit, and decided to check the cam gears themselves. For reference, the red bar in the background is my el cheapo strut tower brace, and it is level.



Exhaust cam... all smiles.

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*drumroll*


Intake cam.

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******* hackjob moron retards who did the timing belt twenty thousand miles ago did that. There are 21 teeth between the two, not 19 like there are supposed to be.

I have dyno time in 6 weeks. I am going to fix that abomination, install COPs and water injection, and see what this turbo will really ******* do.
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Old 04-14-2008, 10:04 PM   #2
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I bet that was a sight for sore eyes!!!

Hello power!!!
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Old 04-14-2008, 10:10 PM   #3
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Bet it didn't have the top end pull you always thought it should. When I bought mine, I knew something wasn't right. I did the regular tune up stuff. Then I did exactly what you just did, and found mine was 1 tooth off, not 2. I'm here to tell you that 1 tooth made a big damn difference on mine for top end power, as well as gas mileage. I'm sure you have a lot to pick up being 2 off.
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Old 04-14-2008, 10:29 PM   #4
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The problem is you should have done this 15k miles ago Sav. Glad you found your problem though.
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Old 04-14-2008, 10:31 PM   #5
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Thats why i hate turning my cars into shops (unless its for paint). If you want **** done right then you got to do it your self.

*Good job on finding the problem*
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Old 04-14-2008, 10:34 PM   #6
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man... I'm surprised you put down 219/201 like that...
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Old 04-14-2008, 10:56 PM   #7
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I don't want to even check the timing on my GTI...that I just changed the belt on...all I know is its close because the car still runs...
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Old 04-14-2008, 11:04 PM   #8
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Quote:
Originally Posted by Arkmage View Post
man... I'm surprised you put down 219/201 like that...
Me too, to be honest. I was always a bit disappointed in the numbers this car produced (202 at 13psi on the .49 A/R, then 219 at 14psi on the .64), but this explains a bunch of it. At least I know the problem now.
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Old 04-15-2008, 12:01 AM   #9
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that's awesome at least that you've found out what's up. Makes me want to double check the previous owners TB job now just to be safe.
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Old 04-19-2008, 03:59 AM   #10
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Fixed the belt, had to retune both fuel and spark almost completely. We aren't done yet, using MLV for fuel and hand-tuning spark via the Knocksense and 4th/5th gear pulls, but here's where we are. Big change from what I was running, and it's not knocking (except when it goes lean).

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Old 04-19-2008, 04:36 AM   #11
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Hmm, the real question though.. How does it FEEL? I would bet its alot better

Are you going to put it back on a dyno now?
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Old 04-19-2008, 05:06 AM   #12
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that is alot better bud
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Old 04-19-2008, 05:11 AM   #13
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Feels a LOT better. A lot more pull low at low rpm.

We pretty much fixed the knocking and will be adding in some timing up top tomorrow probably.

I'm sure there is a lot more area under the curve now, not sure how much higher the numbers are so far though. It will be on a dyno eventually.
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Old 04-19-2008, 05:37 AM   #14
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Ended here for the evening, Did some more pulls in the sub-4k region, had to pull some timing. This turbo is a ******* MONSTER down low.

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Fireindc, it feels much better down low, but up top it's about the same. We still need to add timing in up top, so there's more to be had. I'd say peak torque is probably 500-700rpm lower.
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Old 04-19-2008, 05:44 AM   #15
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25-115, 2k in 4th to 6k in 6th. AFRs are still a bit wobbly, and I am getting knock after the shifts into 5th and 6th from boost overshoot. Internal wastegate FTL.
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Old 04-19-2008, 11:45 AM   #16
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I remember when I had just gotten my Link. The car felt good. I left for a 3 month volunteer service project. When I got back the car felt slow as s#@. Almost a year later i finall figure out my timing was off. My crank pulley had worn apart and was rotating separately from the backing. I set it using a screwdriver and the **** pulled hard . I wish I would have dynoed it after I fixed it.
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Old 04-19-2008, 12:12 PM   #17
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hey you know intake valve timing has a huge effect on the power band. Perhaps you've seen my signature? Only difference is intake valve timing. Advancing helps the low end, retarding helps the high end.

I forget which way the engine rotates though. I think it's clockwise from the drivers seat? If so I believe you were two teeth advanced which is about 30 crank degrees.
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Old 04-19-2008, 03:24 PM   #18
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Quote:
Originally Posted by y8s View Post
hey you know intake valve timing has a huge effect on the power band. Perhaps you've seen my signature? Only difference is intake valve timing. Advancing helps the low end, retarding helps the high end.

I forget which way the engine rotates though. I think it's clockwise from the drivers seat? If so I believe you were two teeth advanced which is about 30 crank degrees.

Best I can figure is that when you're facing the engine, looking at the front, it rotates clockwise, and the intake cam was 2 teeth counter-clockwise, or 30 degrees retarded. It definitely feels weaker on top and much better in the low end.
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Old 04-19-2008, 03:51 PM   #19
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oops I meant counter clockwise from drivers seat. clockwise with your knees against the bumper.

and 30 degrees counter-clockwise (knees-bumper) would be advanced right? it's degrees before top dead center. eg running 30 degrees of spark advance means you ignite while the piston is on its way up.

it should have been ok-ish for low end and better for top end when it's clockwise a tooth.

do you have a dyno plot?
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Old 04-19-2008, 04:36 PM   #20
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I don't think so. If you spun the motor to TDC, and then spun it another 15 degrees (30 cam degrees), but left the intake cam alone, that's where I was, so that's 30 degrees retarded (delayed). Like you said, retarding the intake cam helps top end and hurts low-end, so when I re-advanced it (corrected it) I gained a bunch of low-end power and it's laying flat up top now.

Matt, how many degrees does the VVT let you play with? I know for a fact that bringing the intake cam back to correct, from what was 30 retarded, made a huge gain on low-end power. I'm not going to say anything conclusively about the top end yet, because it's still pretty rich (11.7-12.0 in boost to 6k, and then it tapers off to 10.5) and my timing curve is flat to redline.

No dyno plot yet. Won't happen until the end of May.

Last edited by Savington; 04-19-2008 at 05:03 PM.
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